In the NFL playoffs, momentum turns out to be momentary

SAN FRANCISCO — So much for momentum.

Green Bay had it, having throttled Minnesota in the first round of the NFL playoffs. But the Packers were turned back by a San Francisco team that was two weeks removed from its worst loss of the season.

The Denver Broncos had momentum too, riding an 11-game winning streak into the postseason. They lost at home to the Baltimore Ravens, who had lost four of their last five regular-season games.

Also rolling were the Seattle Seahawks, who had won six in a row, counting their playoff victory at Washington. But, despite an epic comeback Sunday, the Seahawks were beaten by the Atlanta Falcons, who lost two of their final four games in the regular season and were 0-3 in playoff games under Coach Mike Smith.

The only divisional-round winner that had momentum going in and kept it was New England, and the Patriots did what they were supposed to do Sunday, beating Houston at home.

With one Sunday of games left before Super Bowl XLVII, it’s San Francisco at Atlanta, followed by Baltimore at New England.

Four teams left, and four possible Super Bowl permutations:

San Francisco vs. Baltimore — As story lines go, there’s no more intriguing matchup than one that pits coaching brothers Jim and John Harbaugh — a Bros’ Bowl. The two met on Thanksgiving last season, with John’s Ravens beating Jim’s 49ers, 16-6. The brothers lovingly root for each other, but their 2011 meeting was so emotionally taxing for their parents that Jack and Jackie Harbaugh couldn’t stay in the stadium to watch.

San Francisco vs. New England — Tom Brady facing the team he loved as a kid? Randy Moss squaring off against the Patriots, the team that breathed life back into his career? This was a memorable game during the regular season, with the 49ers building a 28-point lead in Foxborough, the Patriots clawing their way back, and San Francisco catching a second wind on its way to a 41-34 victory. That late surge was a prove-it moment for quarterback Colin Kaepernick.

Atlanta vs. Baltimore — A bit of synchronicity: The Falcons and Ravens opened the 2012 exhibition season against each other in Atlanta (Baltimore won the meaningless matchup, 31-17, with Curtis Painter at quarterback). The last time these teams met in a game that counted, Week 10 of the 2010 season, the Falcons won at home, 26-21. Of the four teams in the championship round, Atlanta is the only one without a ring. This game would be a big challenge for marketers to keep the country interested.

Atlanta vs. New England — As Tom Brady was ascending to superstardom, Matt Ryan was creating a legacy of his own at Boston College. Two years ago, when the Patriots and Falcons had a joint practice, Ryan tried to get Brady to open up and share some trade secrets. No luck. Brady was cordial but largely mum. “I don’t blame him,� Ryan said at the time. “I think everybody is protective. Everybody wants a bit of their competitive advantage.�

Before we get to the Super Bowl, of course, there’s championship Sunday, a day that often surpasses the biggest game in terms of excitement.

Ravens-Patriots is a rematch of last season’s AFC championship game, which New England won, 23-20. The Ravens fell apart in the fourth quarter, with Lee Evans dropping a would-be touchdown pass and Billy Cundiff missing a 32-yard field-goal attempt at the end. The teams met again this season in Week 3, with the Ravens winning, 31-30.

At the end of that game, remember, Patriots Coach Bill Belichick grabbed a replacement official by the arm to ask why the Ravens’ winning field goal, a near-miss, wasn’t reviewed.

For the 49ers, the NFC title game means facing their former head coach, Atlanta defensive coordinator Mike Nolan. Considering their porous defense in the second half against Seattle, the Falcons will have their hands full — or worse, empty — in trying to contain Kaepernick, who rushed for 181 yards against the Packers, an NFL postseason record for yards on the ground by a quarterback.

San Francisco has a lot of momentum. And we know what that means.

[For the Record, 4:30 p.m. PST Jan. 15: Baltimore is the only first-round winner to reach the final four. A previous version of this story’s subheadline said New England.]

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